This application is based on and claims the benefit of German Patent Application No. 10211074.3 filed Mar. 13, 2002, which is incorporated by reference herein.
The present invention relates to a pipeline for the transport of refrigerated media.
A pipeline for the transport of refrigerated media, which comprises two corrugated metal pipes, positioned concentrically and at an interval to one another, is known from European Patent Application 0 326 923 A. In such a pipeline, a superinsulator, wound in a helix, made of alternate layers of metal films or metallized plastic films and insulating material positioned on top of one another, are provided in the ring gap between the metal pipes and held in a vacuum.
In order to accelerate the evacuation procedure, a ring gap is provided between the inner pipe and the superinsulator layer, the ring gap formed by a spacer, wound on the inner pipe in a helix, which comprises single strands made of plastic which are braided together.
The advantages of the known pipeline are particularly that lengths of more than 20 m may be evacuated rapidly, and compressions of the superinsulator as a consequence of load pressures of the inner pipe remain restricted to the smallest possible region. Through the improved evacuation, expensive superinsulator material may be dispensed with while keeping the same insulation value, and thus the external diameter of the pipeline may be reduced.
The disadvantage of this known pipe construction is that, due to the proportion of plastics in the thermal insulation, the pipeline cannot withstand higher temperatures over a longer period of time. Thus, for example, in the production of an outer shell through extrusion of a thermoplastic, temperatures of up to 300xc2x0 C. arise on the outer surface of the pipeline. This leads to temperatures of up to 120xc2x0 C. on the inner pipe, so that the insulating material, e.g., metallized plastic films or spacers made of plastic, soften and are no longer able to fulfill their desired function. Incidence of heat on the inner pipe from the outside is possible because during manufacturing the ring gap is not yet evacuated.
The present invention is based on the object of improving the known pipeline in such a way that the pipeline, even if the ring gap is not yet evacuated, may withstand temperatures of over 300xc2x0 C., without parts of the insulating layer losing their desired function. In addition, contact of the inner pipe and outer pipe is to be avoided.
This object is achieved by the a pipeline wherein the spacer (3) is a metal wire (3a), onto which bodies (3b) made of a mechanically resistive insulating material, which are provided with a hole, are threaded at specific intervals and the layers (4b) made of insulating material comprise a nonwoven glass or ceramic.
Further advantageous embodiments of the present invention are described below and in the appended claims.